The invention relates to improvements in pump-motor assemblies, especially in assemblies wherein a motor is used to drive a centrifugal pump. More particularly, the invention relates to improvements in frames for pump-motor assemblies and to improvements in means for and in methods of installing pump-motor assemblies in such frames.
The casings of centrifugal pumps are often subjected to pronounced internal pressures. In order to ensure that the casing of a centrifugal pump will be capable of standing such stresses, it is customary to provide the casing with external reinforcing ribs or to increase the thickness of the casing. Such expedients are also resorted to if the casing is large. These undertakings are intended to prevent expansion of the casing in the event of pronounced internal pressures, to prevent such extensive deformation of the casing that the casing is likely to come in contact with the impeller or impellers and/or to prevent the development of cracks in certain regions of the casing, particularly in the region of the so-called spurs. Reference may be had, for example, to German Auslegeschrift No. 1 135 765 of Klaus (published Aug. 30, 1962). A drawback of the proposal of Klaus is that the pump casing is very expensive, even if the casing constitutes a casting. It is necessary to make complex and expensive cores and patterns which are utilized to carry out the casting operation.
Another prior proposal to reinforce the casing of the pump in a pump-motor assembly or aggregate is disclosed in British Pat. No. 911,769 granted Nov. 28, 1962 to Jonkopings Mekaniska Werkstadts Aktiebolag. This publication discloses a frame which resembles a tripod having three legs resting on a base and supporting the motor of the pump-motor assembly from below. The casing of the pump is suspended from the frame and is disposed between the legs. The patented assembly is bulky and the frame is incapable of ensuring that the pump casing will indeed stand pronounced internal pressures. The reason is that the frame merely serves as a means for propping the motor from below and for releasably holding the pump casing in suspended condition.